'65 with 302 overheating
Thread Starter
Joined: Oct 2009
Posts: 9
From: California
'65 with 302 overheating
Hello:
I have a '65 fastback with a 302 engine that was rebuilt about 40 miles ago. Just after the engine was rebuilt, I shipped the car to Hawaii, so now is the first time I'm really getting a chance to drive it. The engine has been overheating. Here's an example. Yesterday it overheated and a lot of its coolant came out of the radiator overflow tube and from under the radiator fill cap as a combination of liquid and steam. After the engine cooled, we put in about 1 gallon of water to fill the radiator. Today I drove the car around the neighborhood (mostly at 20 mph and under) for 25 minutes. When I parked the car, no steam or coolant from the overflow tube or fill cap. I drove around for another 35 minutes and came back home. I stopped the car on the side of the street with the engine running. Again, no steam or liquid coolant leaking from the overflow tube. So I pulled the car into the garage and shut off the engine. Coolant almost immediately started leaking from the overflow hose and the radiator fill cap. The oil level looks ok as does the transmission fluid. Right now the engine is still a bit hot so I haven't checked the coolant level. Coolant isn't otherwise leaking from the car since the floor of the garage is totally dry when I go to start the car. Unfortunately, the temp gauge on my car doesn't work since there's no water temp sending unit (I'm working on getting that fixed).
Does anyone have some bright ideas as to what could be going on? It seems odd to me that the car would only really start to boil over once the engine is stopped. Feel free to contact me at mconnelley@mac.com.
Cheers
Mike Connelley
I have a '65 fastback with a 302 engine that was rebuilt about 40 miles ago. Just after the engine was rebuilt, I shipped the car to Hawaii, so now is the first time I'm really getting a chance to drive it. The engine has been overheating. Here's an example. Yesterday it overheated and a lot of its coolant came out of the radiator overflow tube and from under the radiator fill cap as a combination of liquid and steam. After the engine cooled, we put in about 1 gallon of water to fill the radiator. Today I drove the car around the neighborhood (mostly at 20 mph and under) for 25 minutes. When I parked the car, no steam or coolant from the overflow tube or fill cap. I drove around for another 35 minutes and came back home. I stopped the car on the side of the street with the engine running. Again, no steam or liquid coolant leaking from the overflow tube. So I pulled the car into the garage and shut off the engine. Coolant almost immediately started leaking from the overflow hose and the radiator fill cap. The oil level looks ok as does the transmission fluid. Right now the engine is still a bit hot so I haven't checked the coolant level. Coolant isn't otherwise leaking from the car since the floor of the garage is totally dry when I go to start the car. Unfortunately, the temp gauge on my car doesn't work since there's no water temp sending unit (I'm working on getting that fixed).
Does anyone have some bright ideas as to what could be going on? It seems odd to me that the car would only really start to boil over once the engine is stopped. Feel free to contact me at mconnelley@mac.com.
Cheers
Mike Connelley
6th Gear Member
Joined: May 2009
Posts: 5,232
From: PA
Is it actually overheating? Coolant should be 1" below the filler neck in the radiator, any higher than that and the natural expansion of the coolant will cause loss.
You should be using a 190° Ford thermostat, with the air bleeder.
It is normal for the coolant temp to spike when the engine is shut off. The engine at full heat, but the cooling system stops.
If the engine was bored oversize, you'll need to have a three-row radiator, fan shroud, and five- or six-blade fan, and not one of those crappy flex fans, either. The best choice is a six-blade thermal clutch fan.
You should be using a 190° Ford thermostat, with the air bleeder.
It is normal for the coolant temp to spike when the engine is shut off. The engine at full heat, but the cooling system stops.
If the engine was bored oversize, you'll need to have a three-row radiator, fan shroud, and five- or six-blade fan, and not one of those crappy flex fans, either. The best choice is a six-blade thermal clutch fan.
6th Gear Member
Joined: Oct 2006
Posts: 6,417
From: Cork, Ireland
check with engine cold. let the car run with the radiator cap off.
the water shouldn't move much. once it warms up and the thermostat opens the water will flow through the radiator and you should see it 'streaming'. check for bubbles coming up eventually.
Did they testrun the engine once tyhey rebuilt it??? or just slap it together and ship?
the water shouldn't move much. once it warms up and the thermostat opens the water will flow through the radiator and you should see it 'streaming'. check for bubbles coming up eventually.
Did they testrun the engine once tyhey rebuilt it??? or just slap it together and ship?
3rd Gear Member
Joined: Aug 2006
Posts: 886
From: North East Texas on the Red River
A Red Flag went up for me when you said that the engine is freshly rebuilt. There are two things you need to check:
Firstly, look at the front outer corners of both cylinder heads where they join the block. If the head gaskets were put on correctly, BOTH of them will have a square corner of the gasket protruding out beyond the edge of the cylinder head. The edge of the cylinder head is sort of rounded, while the edge of the gasket is square. If either of the head gaskets are NOT protruding at this position, then THAT head gasket is on wrong and MUST be replaced taking care to put the end of the gasket marked "FRONT" toward the front of the engine.
If both head gaskets are on correctly, let the engine cool and pull the top radiator hose from the intake manifold and make sure that coolant comes out. Be ready to just pull it off very quickly and stick it back in place if coolant flows. If coolant does NOT flow, then leave the heater hose off and fill the radiator until coolant flows out at this point. As soon as coolant flows, quickly put the hose back in place and continue to fill the radiator.
Check back in here with the answer to these two tests and we will go from there.
BTW, it is not unusual for an engine to overheat at the time it is shut off, because coolant is no longer being circulated. It then just sets there and boils.
Firstly, look at the front outer corners of both cylinder heads where they join the block. If the head gaskets were put on correctly, BOTH of them will have a square corner of the gasket protruding out beyond the edge of the cylinder head. The edge of the cylinder head is sort of rounded, while the edge of the gasket is square. If either of the head gaskets are NOT protruding at this position, then THAT head gasket is on wrong and MUST be replaced taking care to put the end of the gasket marked "FRONT" toward the front of the engine.
If both head gaskets are on correctly, let the engine cool and pull the top radiator hose from the intake manifold and make sure that coolant comes out. Be ready to just pull it off very quickly and stick it back in place if coolant flows. If coolant does NOT flow, then leave the heater hose off and fill the radiator until coolant flows out at this point. As soon as coolant flows, quickly put the hose back in place and continue to fill the radiator.
Check back in here with the answer to these two tests and we will go from there.
BTW, it is not unusual for an engine to overheat at the time it is shut off, because coolant is no longer being circulated. It then just sets there and boils.
Last edited by MBDiagMan; Mar 22, 2010 at 09:20 AM.
2nd Gear Member
Joined: Sep 2009
Posts: 183
From: florida
Hello:
I have a '65 fastback with a 302 engine that was rebuilt about 40 miles ago. Just after the engine was rebuilt, I shipped the car to Hawaii, so now is the first time I'm really getting a chance to drive it. The engine has been overheating. Here's an example. Yesterday it overheated and a lot of its coolant came out of the radiator overflow tube and from under the radiator fill cap as a combination of liquid and steam. After the engine cooled, we put in about 1 gallon of water to fill the radiator. Today I drove the car around the neighborhood (mostly at 20 mph and under) for 25 minutes. When I parked the car, no steam or coolant from the overflow tube or fill cap. I drove around for another 35 minutes and came back home. I stopped the car on the side of the street with the engine running. Again, no steam or liquid coolant leaking from the overflow tube. So I pulled the car into the garage and shut off the engine. Coolant almost immediately started leaking from the overflow hose and the radiator fill cap. The oil level looks ok as does the transmission fluid. Right now the engine is still a bit hot so I haven't checked the coolant level. Coolant isn't otherwise leaking from the car since the floor of the garage is totally dry when I go to start the car. Unfortunately, the temp gauge on my car doesn't work since there's no water temp sending unit (I'm working on getting that fixed).
Does anyone have some bright ideas as to what could be going on? It seems odd to me that the car would only really start to boil over once the engine is stopped. Feel free to contact me at mconnelley@mac.com.
Cheers
Mike Connelley
I have a '65 fastback with a 302 engine that was rebuilt about 40 miles ago. Just after the engine was rebuilt, I shipped the car to Hawaii, so now is the first time I'm really getting a chance to drive it. The engine has been overheating. Here's an example. Yesterday it overheated and a lot of its coolant came out of the radiator overflow tube and from under the radiator fill cap as a combination of liquid and steam. After the engine cooled, we put in about 1 gallon of water to fill the radiator. Today I drove the car around the neighborhood (mostly at 20 mph and under) for 25 minutes. When I parked the car, no steam or coolant from the overflow tube or fill cap. I drove around for another 35 minutes and came back home. I stopped the car on the side of the street with the engine running. Again, no steam or liquid coolant leaking from the overflow tube. So I pulled the car into the garage and shut off the engine. Coolant almost immediately started leaking from the overflow hose and the radiator fill cap. The oil level looks ok as does the transmission fluid. Right now the engine is still a bit hot so I haven't checked the coolant level. Coolant isn't otherwise leaking from the car since the floor of the garage is totally dry when I go to start the car. Unfortunately, the temp gauge on my car doesn't work since there's no water temp sending unit (I'm working on getting that fixed).
Does anyone have some bright ideas as to what could be going on? It seems odd to me that the car would only really start to boil over once the engine is stopped. Feel free to contact me at mconnelley@mac.com.
Cheers
Mike Connelley
I am no engine guru but you should really consider a temperary temp gauge or something. That fresh of a build and no fail safes in place is a recipe for disaster.
2nd Gear Member
Joined: Sep 2009
Posts: 224
From: Central PA
Things that stick out to me is that it didn't do it running, but did at rest. That would lead me to look at the radiator cap (what pressure cap are you running) and how full the radiator was. If you overfill it, it will blow steam/liquid out the overflow tube after being shut down as others above had said. However, you also mentioned that it was coming from around the cap. That also could be a sign that the cap is the wrong pressure or is worn.